<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    /*id选择器*/
    #p1{color:red}
    /*类选择器*/
    .c1{color: blueviolet}
    /*分组选择器*/
    h2,#p1,.c1{background-color: greenyellow}
    /*属性选择器*/
    input[type='text']{background-color: orange}
    /*通配选择器*/
    /* 边框  粗细  实线边框 颜色*/
    *{border: 1px solid red}
  </style>
</head>
<body>
<input type="text">
<input type="password">
<h2>我是h2</h2>
<p id="p1">苹果</p>
<p>香蕉</p>
<p class="c1">橘子</p>
<h3>电视</h3>
<h3>冰箱</h3>
<h3 class="c1">洗衣机</h3>
</body>
</html>